For the distribution of the fresh air or warm air within the passenger compartment of motor vehicles usually air outlet grills are used which are provided with adjusting elements allowing only for the changing of the flow direction. In order that the speed of air flow could also be regulated in the vicinity of the passengers, that is, in order that the cooling or warming effect of the outlet grill could be regulated, the air output from the grill must also be changed. The latter expedient presents, however, difficulties in that in order that the certain climate could be sustained in the passenger compartment, a certain air output must be maintained.
German OLS (layed open application) No. 1,430,300 (63c-74) represents an example for an arrangement having a plurality of vane-shaped air guiding elements which can be pivoted only together, therefore, they allow only for a change of the direction of the exiting air. In the latter paper, all air guiding elements which are arranged in a frame have a common pivoting axis.
DAS No. 1,812,283 (63c-74) on the other hand, provides for vane-shaped air guiding elements which are pivotable about an individual axle, which, however, in order to perform a common pivoting movement, are connected by transverse webs. Also in this literature, when the air guiding elements are operated, only a changing in the direction of the air flow is attained, however, without attaining a change in the flow speed at the vicinity of the body exposed to the air flow.
The arrangement according to U.S. Pat. No. 2,790,371 issued Apr. 30, 1974 differs from the above-discussed technical literature in that the lamellae or vane-shaped air guiding elements used by the patented structure can be pivoted independently from each other always about one of several parallel and adjacently lying pivot axles. The structure of the aforementioned patented air outlet grill provides also the possibility for pivoting the outer lying vanes with respect to each other in such manner that they enclose an angle with respect to each other directed along the air flow. On the other hand, the independent pivotability of the different air guiding elements provides also the possibility of creating angles directed in opposite directions, so that such known arrangement provides not only for the possibility of changing the flow direction, but also provides the possibility of changing the width of flow and thereby the speed of flow in the vicinity of the body exposed to the air flow.
The last-mentioned arrangement is, however, somewhat difficult to handle in practical use by the passengers of a motor vehicle since it requires the adjustment of a plurality of vanes individually. In the embodiment illustrated in the aforementioned patent, there are four guiding elements which are to be adjusted independently from each other which fact represents a rather complicated expedient for the users of the motor vehicle who, in most case, are technically untrained.